Switching apparatus



, April 22, 1924. 1,491,440

E. THOMSON SWITCHING APPARATUS Filed June 2, 1921 1/7 z/eno/r E0770Thomson,

Patented Apr. 22, 1924.

UNITED STATES PATENT OFFICE.

, ELIEU THOMSON, OF LYNN, MASSACHUSETTS. ASSIGNOB 'IO GENERAL ELECTRICCOKPAN Y, A CORPORATION OF NEW YORK.

SWITCHING APPARATUS.

Application fled. June}, 1921. Serial No. 4474.,886.

To all whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States,residing at L nn, in the county of Essex, State of i assachusetts, haveinvented certain new and useful Improvements in Switching Apparatus, ofwhich the following is a specification.

The present invention relates to an improvement in circuit breakingapparatus for electric circuits, and its object is to obviate so far aspossible any injury to a switch on openin a circuit due-to the are whichgenerally ollows such opening until the switch terminals are so farapart as to exceed the potential which sustains the arc. To this end theswitching contacts are provided with shunt means, such as 'avacuumdischarge device, and a jet of air, or other fluid, is caused to playbetween the switch contacts as they open. The accompan ing drawingillustrates one embodiment o my invention in a simple hand-operatedswitch. In thefigure, a source of current 1 may 'll be represented by ad namo or like apparatus supplying a loa 2 b a circuit 3, 4, containinga switch control ing the passage of current to this load and havingcontacts 5. The switch arm 7 is mounted upon the so insulating plate 8of a receptacle 9 containing a vacuum discharge device 10 connected inshunt to switching contacts 5 by the conductors 11, 12. The electrodes13, 14 of the discharge device, consisting res tively of It brass andaphite, are separate by a-small space, and ave a considerable surfacewhere opposed to each other. The discharge device 10-contains a suitableattenuated example, ar on. This well-known orm of to vacuum disc rgedevice is described in general in U. S. patent to Creighton No. 1,144,-028 of 1915, and in patent application, Serial No. 240,664, filed June18, 1918, by George B. Philli s.

At the time- 0 opening the switch contacts 5 a jet of air or other gassupplied by the pipe or conduit 15 passes between the contacts. Theoperation is as follows: Immediately upon the slightest separation of 00contacts, the jet from the pipe 15, forces any spark-.or arc dischargeover to the far thest int' awa from the jet. This action great y raisese impedance of the ionized s, for

air gap. Consequently, the potential across the contacts will riseconsiderably above the normal, especially if there is any reactance I Iin the circuit as diagrammatically indicated at 16. This increase ofpotential causes a dischargein the vacuum tube in which a blue orpurplish flash appears, and the circuit is then open. The ener whichwould go to damage the switch is t us transferred lnstantl to the vacuumdischarge device and is t ere disposed of harmlessly. If, for example,the circuit to be opened is 220 volts, th1s voltage would tend tomaintain a considerable are at the breaking or opening of the contacts.At the very incipiency of such an arc, the jet drives it over frombetween the contacts, and the potential takes such a sudden rise thatthe vacuum tube gap,

though set for sa 500 or 600 voliz, 1s umped, but the disc argeimmediately because it cannot be maintained by the normal voltage of theline through the vacuum chamber. It has been found that the operation ofsuch a switch may be performed man thousands of times without appreciabinterfering with the integrity of the switc surfaces.

The utility of my invention to the commutation of high voltagealternating currents and various other apphcations will appear from the,foregoing without further ex lanation.

hat I claim as new and desire to secure by Letters Patent of the UnitedStates, is 1. A circuit breaking apparatus comprising the combination ofswitching co'ntacts,-a vacuum discharge device connected in shuntthereto, and means for increasing the impedance of the gap1 between saidcontacts to an electrical disc arge occurring between said contacts.

2. A circuit breakin apparatus comprising the comb nation 0 switchincontacts, cooperating. electrodes in shunt t eneto separated by a gap,and surrounded by an attenuated gas, and a blow out device for lenhening an electric discharge between sai contacts.

3. A circuit breaking apparatus comprising the eombinationof switchincontacts, cooperating electrodes in shunt thereto separated byv a gapand surroundedby an attenuated gas, and'a nozzle delivering a blast seesof gas transversely to said contacts whereby an electrical dischargebetween the same will be lengthened.

4. A circuit breaking device comprising I the combination of a pair ofswitching contracts, a discharge device connected in shunt with saidcontacts and having a breakdown voltage above the normal voltage of saidcircuit, and means for causing a sudden increase in the impedance of thegap formed by the separation of said contacts whereby the resultingenergy discharge of said circuit is transferred to said dischargedevice.

In witness whereof, I have hereunto set my hand this 31st da of May,1921.

E IHU THOMSON.

